Thermo-economic optimization of the dual-pressure condenser for 700 °C ultra-supercritical coal-fired power plants

Pulverized coal power is one of major contributor in power production, whose efficiency can be enhanced by increasing the main steam parameters and adjusting the cold end system parameters. The thermo-economic optimization of the cold end system for 700 °C ultra-supercritical coal-fired power plants were carried out in this study. The condenser pressure was thermoeconomically optimized for the single-pressure condenser systems. Then, with the same heat transfer area of the optimized single-pressure condenser, the dual-pressure condenser system was thermo-economically optimized. The distributions of heat transfer area and exhaust steam mass flow between the highpressure and low-pressure chambers in the dual-pressure condenser system were optimized. The results show that the optimal vacuum pressure of the single-pressure condenser is 3 kPa and the optimal heat transfer area is 27 km2. For the dualpressure condenser system, the cost of dual-pressure condenser is reduced to the minimum value 1.3 million CNY/year. The power plant efficiency is increased by the maximum value 0.1% when the heat transfer area and exhaust steam mass flow rate are distributed equally between two chambers, compared with that of the single-pressure condenser system. The optimal values of the low-pressure and high-pressure chamber are 2.4 kPa and 3.2 kPa, respectively. This paper provides the reference for the design optimization of cold end system for high parameter power units.